Hi, David,
On 8/15/2016 9:23 AM, David Allan I wrote: > > So long as we are running down this rabbit hole…. J > > > > My very original comment was “if this is a use case document, why is > this concept in here with no associated use case for why I would need > it? Could we have a use case please” > > > > As the comment referred to multiple subnets, I would then observe that > as far as IP is concerned, a subnet traditionally corresponds to a > broadcast domain. These days I do not necessarily need to implement it > via traditional bridging, and a lot of traditional discovery is > changing to being database driven configuration. But I would have no > trouble noting that a broadcast domain that also corresponds to a > subnet has useful properties at a bunch of levels as a subnet > prefix/mask becomes a convenient shorthand for the set, although a VNI > is an even more convenient shorthand J But if I want to run a single > network as if it were a subnet using established tools, fine…. > > > > What I am less clear on is constructing a virtual network of multiple > subnets and creating a virtual topology when AFAIK this does not get > me much. > You get the ability to scope these discovery domains in ways that correspond to IP address ranges, which is already widely used in IP. I.e., you get to emulate how IP works. > Am I simply scaling a single community of interest to which common > policies apply? IN which case most of the properties a broadcast > domain gets me, I’d want to see at L3. Am I defining relationships > between dissimilar communities of interest, which is wildly > overloading the concept… As noted above policy could equally be > expressed as VNI relationships, which likely is an equally useful > abstraction. > The way in which these subnets are implemented may vary, as may the discovery mechanism. But having them correspond to IP address ranges has the direct benefit of emulating *existing* behavior of IP. Let's put it another way - if you don't allow IP subnet virtualization, you end up with a virtual network on which some IP topologies cannot be deployed. That's an unnecessarily limitation. Joe > > > I hope this is clear > > Dave > > > > *From:*Joe Touch [mailto:[email protected]] > *Sent:* Saturday, August 13, 2016 10:30 AM > *To:* David Allan I <[email protected]> > *Cc:* [email protected]; Bocci, Matthew (Nokia - GB) <[email protected]> > *Subject:* Re: [nvo3] FW: Call for interest on NVO3 use case draft > > > > > > On 8/13/2016 9:52 AM, David Allan I wrote: > > Hi Joe > > > > And the use case for wanting to do subnet emulation is….? > > > You want the properties of a subnet and/or to emulate the behavior of > a shared link, i.e., to limit the scope of various protocols, > including IP routing, IPv6 automatic addressing, L2 address > translation (virtualizing L2 underneath a virtual L3 is needed to > support revisitation, where a single node participates multiple times > in an overlay), and basically any subnet-based resource discovery. > > Joe > > > > > That‘s my question > > Dave > > > > *From:*Joe Touch [mailto:[email protected]] > *Sent:* Friday, August 12, 2016 8:20 PM > *To:* David Allan I <[email protected]> > <mailto:[email protected]> > *Cc:* [email protected] <mailto:[email protected]>; Bocci, Matthew (Nokia > - GB) <[email protected]> <mailto:[email protected]> > *Subject:* Re: [nvo3] FW: Call for interest on NVO3 use case draft > > > > The typical use case is to support subnet emulation, e.g., a group > of links over which broadcast is emulated as with LANE. > > > On Aug 12, 2016, at 7:11 PM, David Allan I > <[email protected] <mailto:[email protected]>> > wrote: > > My point would be that introducing additional complexity in > an overlay should have a use case associate with it. It would > not be something you would do gratuitously…. > > > > SO I’m looking for the draft to provide a use case for this > vs. simply mentioning subnetting without any context J > > > > Cheers > > Dave > > > > *From:*nvo3 [mailto:[email protected]] *On Behalf Of *Joe > Touch > *Sent:* Friday, August 12, 2016 5:07 PM > *To:* David Allan I <[email protected] > <mailto:[email protected]>>; [email protected] > <mailto:[email protected]>; Bocci, Matthew (Nokia - GB) > <[email protected] <mailto:[email protected]>> > *Subject:* Re: [nvo3] FW: Call for interest on NVO3 use case draft > > > > > > > > On 8/12/2016 4:16 PM, David Allan I wrote: > > 4.2 Why I would subnet my overlay could use some > explanation. I normally think of subnetting as a > convenient address summarization technique dependent on > topology, and with an overlay I don’t have a topology. > > > The topology of an overlay is determined by its tunnels, just > as the topology of the underlying net is determined by its links. > > A subnet in an overlay corresponds either to a single > multipoint tunnel or to a set of tunnels that transparently > acts as such - just as a subnet in the Internet base network > corresponds to a shared access link or a set of links that > transparently act as such (e.g., switched ethernet). > > Joe > > >
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